The Australian Transport Safety Bureau (ATSB) is Australia's national transport safety investigator. The ATSB's function is to improve safety and public confidence in the aviation, marine and rail modes of transport. The ATSB is Australia's prime agency for the independent investigation of civil aviation, rail and maritime accidents, incidents and safety deficiencies.

Centrum Naukowo-Produkcyjne-PZL PZL-104, VH-PZS

The pilot had set up a small business conducting charter flights
and towing advertising banners with his four-place aircraft. For 18
months he had operated from the airstrip near Dunwich, located in a
shallow valley. The surrounding sand hills are timbered and shelter
the strip from the full effects of the prevailing south-easterly
winds.

Two families had earlier arranged a joy flight for three of
their children. Due to adverse weather conditions, the pilot twice
cancelled the proposed flight. On the day of the accident, the
families met the pilot at Dunwich airstrip. He was waiting,
standing near his aircraft with its engine running. After a short
safety briefing, the passengers were seated and strapped in. The
aircraft taxied to the northern end of the 800-metre airstrip where
it held its position presumably while the pilot conducted
pre-takeoff checks. Witnesses heard the engine RPM change several
times before the take-off roll commenced.

Witnesses reported that following a short take-off run, the
aircraft climbed steeply at an angle of approximately 30 degrees.
At top of climb, about 250 ft above ground level, the aircraft
banked steeply to the left. The nose of the aircraft fell below the
horizon during the left turn which continued through 150 degrees.
The aircraft struck the ground, in a 50-degrees nose-low attitude,
in low scrub 120 metres east of the airstrip. A fuel fire started
almost immediately. The parents of the passengers and other
bystanders ran several hundred metres to the crash site. Despite
their efforts they were unable to free the occupants from the
distorted structure. An intense fire drove them back and eventually
burnt out the remains of the cabin.

The pilot's last aircrew medical examination was conducted on 18
May 1995. He held a valid Class 1 medical certificate. His
commercial pilot licence was current and he was endorsed to fly
tail-wheeled aircraft. His pilot's logbook and aircraft records
showed that he had flown fewer than 70 hours in the preceding two
years.

Records showed that the pilot had not undertaken an aeroplane
flight review within the previous two years. His last documented
aeroplane conversion training (which the Civil Aviation Safety
Authority accepts as equivalent to an aeroplane flight review) was
completed on 17 November 1993.

The instructor who conducted the conversion training said that
the pilot's aircraft handling met the minimum required standard and
that he had limited flying experience. The instructor advised the
pilot to operate under an experienced chief pilot until he gained
further flying experience. The pilot declined, saying that he
wanted to run his own operation.

Within the preceding five months, several fellow pilots had on
separate occasions observed the pilot flying his aircraft in an
excessively steep climb after takeoff, followed by an early,
low-speed turn. When they mentioned the implications of his conduct
to him, the pilot responded by saying that the aircraft was
designed for short takeoff and landing. He had been alone in the
aircraft on these occasions. The impression given to people close
to the pilot was that he regarded his aircraft as very stable and
forgiving.

In early June 1995, the pilot was identified flying below 500 ft
along the City Reach and the Toowong Reach of the Brisbane River in
his distinctive aircraft. Neither the pilot's takeoff practice of
climbing steeply, nor the low flying occurrence, was reported to
the Civil Aviation Safety Authority.

The pilot worked from 0100 to 0500 EST as a cleaner at a
supermarket. He had worked this shift schedule on at least four
consecutive mornings the week of the accident, including the day of
the accident. He had also flown a charter flight on the afternoon
before the accident. On a typical work day, he normally slept after
returning from work until about 0900, and again from about
2000/2100 until after midnight, then rose in time to go to
work.

The postmortem examination report did not reveal any
pre-existing physiological problems which could have affected the
pilot's ability to fly the aircraft.

Air operator's certificate

On 16 February 1994, the Civil Aviation Authority (now the Civil
Aviation Safety Authority) issued an air operator's certificate
authorising the pilot to conduct charter and aerial work flights in
his aircraft. When the certificate was issued, the Authority's
policy was to inspect each operator once in every 12-month period.
The inspection specified is limited to an examination of records,
recording systems and facilities. The policy was changed in October
1995, requiring an inspection once in every 18-month period. An
inspection of the pilot's operation had been scheduled for
September 1995 but this was deferred indefinitely due to a high
workload in the Authority's Archerfield office. In addition, the
pilot had not been available for an inspection on an opportunity
basis when the flying operations inspector's schedule
permitted.

The inspection policy change, coupled with delays in scheduling,
resulted in a lack of any periodic inspection of the pilot's
operation. The flying operations inspector in charge of overseeing
the operation said that, had he known of the pilot's potentially
dangerous flying habits and the low-flying occurrence, he would
have investigated. In addition, the Authority was unaware that the
pilot's aeroplane flight review was not current. Legislation does
not require notification that a review has taken place. The
responsibility of keeping the aeroplane flight review valid rests
with the pilot.

Aircraft information

The aircraft was manufactured in Poland and first registered in
Australia on 1 November 1989. It was designed as a light utility
aircraft for the short take-off and landing role. It was a fixed
landing gear, tail-wheeled aircraft, equipped to carry a pilot plus
three passengers. Available aviation literature and flight test
reports highlighted the docile, power-off stall characteristics of
the aircraft.

The aircraft's logbook showed that it had undergone a periodic
maintenance inspection on 15 November 1995. The current maintenance
release was invalid due to an omission by the licensed aircraft
maintenance engineer. He had been unable to document the aircraft
hours limitation as the pilot had not given him the expired
maintenance release as proof of total hours flown. The new
maintenance release was partially destroyed in the fire. As a
result, the number of hours flown since the last periodic
inspection could not be determined accurately, but was estimated to
be in the order of 6 to 10.

No evidence was found in the maintenance records to suggest that
the aircraft was not fully serviceable before the flight.

The managing director of the aviation firm which imported four
PZL-104 had extensive experience flying the type. He said that the
aerodynamic stall characteristics in level flight, power off, were
very docile. Control could be regained by releasing the back
pressure on the control stick. The aircraft stalled at about 38
knots with take-off flap selected. However, when the aircraft
stalled in the take-off configuration with flap and full power, it
rolled rapidly to the left, adopting a distinctly nose-low
attitude. The altitude lost in the recovery was significant but
would depend on how far the nose dropped below the horizon before
the pilot reacted and regained control.

Wreckage examination

The wing structure was largely intact with only the centre
section burnt. It was separated from the fuselage. The left wingtip
struck the ground first and ground marks revealed that the aircraft
was rotating left at impact. Take-off flap (21 degrees) was
selected. The destruction pattern of the wooden propeller indicated
that the engine was producing a significant amount of power at
impact. Witnesses said that the engine noise did not seem to vary
during the entire take-off /accident sequence. The engine was
dismantled in an engineering workshop. Nothing was found which
could have prevented normal engine operation.

The cabin area was destroyed by the impact and subsequent
fuel-fed fire. All flight controls were checked and found to be
free of pre-existing defects. Information received from the public
initially cast doubt on the integrity of the pilot's seat/seat
rail. Apparently, in several occurrences in Poland, the pilot's
seat had been known to slide back on its rails, leaving the pilot
unable to move the control stick far enough forward to regain
control. Detailed examination of the seat-lock mechanism and rail
found that the seat had not moved from the forward position.

Computations of the aircraft weight found that the maximum
allowable take-off weight of 1,300 kg was exceeded by 40 kg. Due to
the excess weight, the aircraft loading was outside the limits
published in the centre-of-gravity graph.

Weather

A ridge of high pressure established along the coast, directing
a moderate to fresh south-easterly airflow onto the coast and
islands. The surface wind was estimated to have been a
south-easterly at 10 knots. Winds at 500-1,000 ft were stronger at
15-20 kts. Witnesses at the airstrip commented that they noticed
the occasional stronger gust of wind.

Aircraft performance

Evidence indicated that the pilot probably initiated a steep
climb after takeoff. With an excessively steep climb attitude, the
aircraft's airspeed decreased rapidly, resulting in an aerodynamic
stall, either at the top of climb or when the pilot rolled the
aircraft into a left turn. Considering the aircraft's low altitude
and the rapid attitude change in a power-on stall, the pilot would
not have been able to regain control in time to avoid a collision
with the ground. The pilot did not appear to detect or correct the
potential problem arising from the aircraft performance in
sufficient time to prevent the stall.

Contributing factors to the pilot's actions

Several factors appeared to contribute to the pilot's use of a
steep climb attitude and his failure to detect or correct the
potential problem in the aircraft's performance.

Firstly, the pilot appeared to believe that the aircraft was
very stable and forgiving. This belief may have resulted in the
pilot developing an undesirably low perception of the risk
associated with some manoeuvres, particularly flying the aircraft
with high rates of climb and low speeds after takeoff. After
repeatedly flying this manoeuvre without adverse consequences it
may have become part of his normal behaviour.

Secondly, the pilot had a relatively low level of overall flying
experience, including recent flying experience. This meant that he
was probably still encountering a significant workload during the
take-off and climb phases. Consequently, he had only a limited
amount of information processing capacity available to deal with
the detection and resolution of a rapidly deteriorating situation.
His low level of experience is also likely to have limited his
familiarity with the nature of an impending stall.

One particular area in which the pilot appeared to have had
limited understanding concerned the effect that different loads
have on the aircraft's performance and capabilities. On the
previous occasions in which the pilot was seen to have used a steep
climb after takeoff followed by an early turn, there had been no
passengers. The aircraft weight was therefore significantly below
the maximum allowable take-off weight. However, on the accident
flight, the aircraft weight was above the maximum allowable
take-off weight. With a heavier than usual aircraft, the
performance would not have been what the pilot normally
experienced. In addition, the centre of gravity was further aft on
the joy flight compared to a pilot-only flight, resulting in a
lighter elevator control. The pilot's low level of experience may
have meant that he was less able to associate a problem with
aircraft performance to the heavier than normal operating
weight.

Finally, the pilot was probably suffering from a significant
level of fatigue at the time of the accident. Research has shown
that working shifts during the critical hours between midnight and
0600 can lead to disruption of the human circadian rhythm. This
disruption is due to physiological and environmental factors, as
well as the social aspects of trying to sleep during the day when
family matters and environmental noise may hamper sleep. Under
these conditions the duration of sleep may be similar to that
associated with a typical work schedule, but the quality of sleep
obtained is usually less than optimal. A lack of quality sleep over
a period of several days can be associated with a significant level
of fatigue.

If the pilot was suffering from fatigue, many aspects of his
performance may have been affected. The effects of fatigue may be
exhibited in the form of slower reaction time, decrease in his
perception and processing of incoming information, poor judgement,
and inappropriate decision making. In other words a significant
level of fatigue would probably have influenced the pilot's ability
to detect and correct a potential problem with the aircraft
performance.

Surveillance by the Civil Aviation Safety
Authority

Evidence showed that some fellow pilots made unsuccessful
attempts to dissuade him from his questionable take-off habit. The
relevant Civil Aviation Safety Authority flying operations
inspector had not been made aware of the pilot's technique of
climbing steeply after take-off. If these events had been reported,
an early investigation may have had the effect of modifying his
flying techniques.

Weather

Witnesses at the air strip report that the wind was gusting
occasionally. It is possible that a stronger gust of wind
exacerbated the handling problem experienced by the pilot.

The pilot's flying habits probably resulted in the adoption of
an excessively steep climb after takeoff.

The aircraft stalled at low altitude and struck the ground
before the pilot could regain control.

At a result of the investigation into this occurrence, the
Bureau of Air Safety Investigation forwarded the following interim
recommendation to the Civil Aviation Safety Authority on 4 November
1996:

'IR960127
The Bureau of Air Safety Investigation recommends that the Civil
Aviation Safety Authority:

review the Aviation Safety Surveillance Program to ensure that
new commercial operators are adequately monitored and inspected
until a demonstrated history of safe operation is known;

align the scheduled surveillance period of the Aviation Safety
Surveillance Program to that of the validity period of the air
operators certificate;

reconsider the flight review requirements for Chief Pilots with
the view of bringing them into line with the current situation for
Chief Flying Instructors, as an additional method of
surveillance;

review the adequacy of the approval and assessment requirements
for Chief Pilots who do not have a demonstrated history in flight
operations with a commercial operator;

review the current situation regarding Aeroplane Flight
Reviews, to allow for appropriate notification to the Civil
Aviation Safety Authority and recording of the results.'

Evidence indicated that the pilot probably initiated a steep climb after takeoff. With an excessively steep climb attitude, the aircraft's airspeed decreased rapidly, resulting in an aerodynamic stall, either at the top of climb or when the pilot rolled the aircraft into a left turn. Considering the aircraft's low altitude and the rapid attitude change in a power-on stall, the pilot would not have been able to regain control in time to avoid a collision with the ground. The pilot did not appear to detect or correct the potential problem arising from the aircraft performance in sufficient time to prevent the stall.

Contributing factors to the pilot's actions

Several factors appeared to contribute to the pilot's use of a steep climb attitude and his failure to detect or correct the potential problem in the aircraft's performance.

Firstly, the pilot appeared to believe that the aircraft was very stable and forgiving. This belief may have resulted in the pilot developing an undesirably low perception of the risk associated with some manoeuvres, particularly flying the aircraft with high rates of climb and low speeds after takeoff. After repeatedly flying this manoeuvre without adverse consequences it may have become part of his normal behaviour.

Secondly, the pilot had a relatively low level of overall flying experience, including recent flying experience. This meant that he was probably still encountering a significant workload during the take-off and climb phases. Consequently, he had only a limited amount of information processing capacity available to deal with the detection and resolution of a rapidly deteriorating situation. His low level of experience is also likely to have limited his familiarity with the nature of an impending stall.

One particular area in which the pilot appeared to have had limited understanding concerned the effect that different loads have on the aircraft's performance and capabilities. On the previous occasions in which the pilot was seen to have used a steep climb after takeoff followed by an early turn, there had been no passengers. The aircraft weight was therefore significantly below the maximum allowable take-off weight. However, on the accident flight, the aircraft weight was above the maximum allowable take-off weight. With a heavier than usual aircraft, the performance would not have been what the pilot normally experienced. In addition, the centre of gravity was further aft on the joy flight compared to a pilot-only flight, resulting in a lighter elevator control. The pilot's low level of experience may have meant that he was less able to associate a problem with aircraft performance to the heavier than normal operating weight.

Finally, the pilot was probably suffering from a significant level of fatigue at the time of the accident. Research has shown that working shifts during the critical hours between midnight and 0600 can lead to disruption of the human circadian rhythm. This disruption is due to physiological and environmental factors, as well as the social aspects of trying to sleep during the day when family matters and environmental noise may hamper sleep. Under these conditions the duration of sleep may be similar to that associated with a typical work schedule, but the quality of sleep obtained is usually less than optimal. A lack of quality sleep over a period of several days can be associated with a significant level of fatigue.

If the pilot was suffering from fatigue, many aspects of his performance may have been affected. The effects of fatigue may be exhibited in the form of slower reaction time, decrease in his perception and processing of incoming information, poor judgement, and inappropriate decision making. In other words a significant level of fatigue would probably have influenced the pilot's ability to detect and correct a potential problem with the aircraft performance.

Surveillance by the Civil Aviation Safety Authority

Evidence showed that some fellow pilots made unsuccessful attempts to dissuade him from his questionable take-off habit. The relevant Civil Aviation Safety Authority flying operations inspector had not been made aware of the pilot's technique of climbing steeply after take-off. If these events had been reported, an early investigation may have had the effect of modifying his flying techniques.

Weather

Witnesses at the air strip report that the wind was gusting occasionally. It is possible that a stronger gust of wind exacerbated the handling problem experienced by the pilot.